The invention relates to a circular saw, in particular a hand circular saw, having a workpiece support surface, a saw blade and a protective cover, which covers the saw blade in a region above a workpiece to be processed.
Chip deflection is extremely important for hand circular saws, above all for metal saws, so that the hot chips flying around cannot fly at the operator. For this reason, arch-shaped protective covers are drawn around the upper half of the saw blade. These protective covers terminate with a flat so-called support plate. The lower side of the flat support plate forms the workpiece support surface, with which the circular saw slides along the surface of the workpiece.
Precisely in the case of metal circular saws, there is the problem that the often transparent or partially transparent protective covers become matted when the hot metal chips strike them.
The object of the invention is allowing an improved chip removal from the circular saw.
This is achieved by a circular saw of the type mentioned at the outset in that the protective cover has such a geometry and position with regard to the saw blade, that a straight line, which originates from the first deflection of a tangent applied at the intersection of the saw blade circumference with the workpiece support surface from the protective cover, encloses an angle of up to 30°, in particular of up to 20°, with a line perpendicular to the workpiece support surface.
The chip flies away linearly from the intersection of the saw blade circumference with the workpiece support surface and describes a straight trajectory, which is determined by the tangent on the saw blade circumference. The chip hits the protective cover and ricochets off, i.e., deflects, wherein the angle of impact is equal to the angle of deflection. The trajectory of the ricocheted chip after its first deflection, i.e., after the first impact on the protective cover, also describes a straight line. However, this straight line does not run in the direction of the operator's arm, as in the prior art, but essentially perpendicular to the workpiece support surface, i.e., in an angular range of ±30° to the perpendicular. If the workpiece support surface is aligned horizontally, then the chips fly essentially vertically. The result of this is improved protection, on the one hand, and, on the other hand, the interior of the protective cover is not stressed as much, because the impact angle of the chip on the inner side of the protective cover is very flat as compared to the prior art. In order to achieve this flat angle of impact, the protective cover is pulled very close to the saw blade as compared to the prior art.
The distance, and namely the shortest distance of the protective cover measured in the region of the workpiece support in the radial direction, is a maximum of 10 mm from the circumference of the saw blade.
In addition, as an alternative to this short distance, the tangent hits the protective cover at a distance of a maximum of 20 mm from the workpiece. This short distance also ensures that the speed of the chip is reduced very quickly, because it bounces off the protective cover at an early stage.
The aforementioned object is also attained or the aforementioned solution is improved in that the protective cover has axially opposing side walls, which partially cover the saw blade in the axial direction, and in that the strips, which run axially toward one another and preferably concentric to the saw blade, project from the inner side of the side walls radially inwards of the saw blade circumference. These strips or arch-shaped extensions, which extend towards the side surface of the saw blade without making contact therewith, shield the toothed circumference of the saw blade radially inwardly somewhat, so that a type of chamber to accommodate chips is produced. This is supposed to prevent chips from being able to leave the protective cover in the direction of the center of rotation.
The protective cover has a viewing area, i.e., at least one viewing area, which clears a view of the cutting site. This viewing area preferably abuts the workpiece support surface.
In order to keep the viewing area, which is formed in particular by a transparent plastic, from becoming matted because of the hot chips, according to the invention, a separate baffle plate is provided on the radial inner side of the protective cover. The metal chips therefore have their first contact with this baffle plate.
According to the preferred embodiment, the baffle plate is made of metal.
In the region of or around the baffle plate, the protective cover is made of transparent plastic so that the view of the cutting site is obstructed only by the metal plate, something that is not annoying overall, and especially since the plastic around the baffle plate does not get matted.
In order to fix the baffle plate in an optimal manner, it is fastened internally on the rest of the protective cover, i.e., the protective cover is at least two layers in the region of the baffle plate, as viewed in the radial direction. The baffle plate may also be fastened on the rest of the protective cover so that it is replaceable, which is advantageous in particular in the case of metal circular saws.
According to the preferred embodiment, the protective cover has a main section. This main section serves to fasten the protective cover on the tool side and is preferably made of non-transparent material. In a normal case, the main section will also form the largest portion of the protective cover and also serves as the support member so to speak.
The main section in this case may be made of another material than the baffle surface and the viewing area, preferably a non-transparent plastic.
It must be emphasized that the viewing area may be designed under some circumstances as an open inspection window or a combination of an open inspection window with a transparent cover.
In addition, an embodiment is also conceivable in which the viewing area, baffle surface and main section are made of transparent plastic.
Besides the baffle surface with the baffle plate, which is provided for the first deflection of the chips, additional baffle plates may also be provided internally on the protective cover in order to prevent damage to other heavily stressed regions of the protective cover. This is advantageous in particular in the case of a plastic design of the protective cover.
Additional features and details of the invention are disclosed in the following description and in the drawings to which reference is made.